Referring to FIG. 3, a conventional injection mold 80 comprises a movable die 81 and a stationary die 82. The movable die 81 comprises a movable die fixing plate 811, a spacer plate 812, an ejection pin plate 813, an ejection pin fixing plate 814, a punch template 815, an ejection pin 816, and a guide rod 817. When the movable die 81 is assembled, it is general to insert the ejection pin 816 into ejection pin holes (not shown) of the ejection pin plate 813 and the punch template 815, and then fasten the ejection pin fixing plate 814 to the ejection pin plate 813 for preventing the ejection pin 816 from being ejected out. Then, the guide rod 817 is inserted into the punch template 815, the ejection pin fixing plate 814, the ejection pin plate 813, and the movable die fixing plate 811.
However, in the above-mentioned assembling method of the injection mold 80, the guide rod 817 can not achieve the positioning function before the ejection pin plate 813 and the ejection pin 816 are assembled. Moreover, the installation of the guide rod 817 is fulfilled by whacking to be inserted into the punch template 815, the ejection pin fixing plate 814, the ejection pin plate 813, and the movable die fixing plate 811. Consequently, in the assembling processes, the guide rod 817 may make the ejection pin plate 813 and the ejection pin fixing plate 814 deformed or wrapped due to elastic deformation. Further, this may cause the injection mold 80 uneven, and result in deforming the ejection pin plate 813 due to unequal forces, breaking the ejection pin 816, and the problem of abrasion in the return stroke. In addition, the guide rod 817 is disposed into the movable die fixing plate 811 and the punch template 815 generally in an interference fitting manner. The guide rod 817 may get loosened and thereby refracted due to the counterforce generated by repeated position motion of ejection and retraction during opening and closing the injection mold 80.